>I remembered after I had made my first reply to this post, that the key thing that Dave Fulton had done was find techniques from mainframes and apply them to PCs. So, that they were denied patents is no surprise.

Now that you mention it, I remember a deja vu I had when I first looked at a hex dump of a .cdx - it somehow resembled the compact indexes found in VAX's RMS. Not same at all, RMS was just discarding trailing spaces in strings, Rushmore was the extra mile in the same direction.